The present invention relates to an apparatus for closing a door of a vehicle, and more particularly to a door closing apparatus for bringing a door which is in a half-closed or latched condition automatically into a full-closed or latched condition.
Prior art attempts to produce a full-closed condition of a side door of a vehicle rely on the use of a structure which engages a striker which is a member of the body side of the vehicle with a latch comprising a part of a door lock apparatus provided on the side door. Referring to FIG. 8, there is shown a latch 1 which is universally pivotal around a pin 2 and which forced to be in one direction at all times due to the urging force of a spring 3. The latch 1 includes an engaging groove 5 receiving a striker 4, a first projection 6 producing the full-closed condition of the door in a periphery thereof, and a second projection 7 making the half-closed condition of the door, to have a protrusion 9 of a pawl 8 universally engaged with both projections 6 and 7.
The pawl 8 is universally pivotal around a pin 9' and forced to stay in the direction of the latch 1 at all times by a spring 10. The pawl 8 is rotatable counterclockwise by the movement of a pin 11' of a lift lever 11 of the opening system of the door lock mechanism.
When the door is in the open condition, the engaging groove 5 lies in the right direction as viewed in FIG. 8, and the protrusion 9 of the pawl 8 comes in contact with an outer periphery of the latch 1. Through the door closing operation, the striker 4 enters the engaging groove 5 and rotates the latch 1 forcibly counterclockwise, whereafter the protrusion 9 engages the second projection 7 to produce the half-closed condition of the door or the half-latch status, while a further door-closing operation permits the protrusion 9 to engage the projection 6, thus producing the full-closed condition of the door or the full-latch status (a condition shown in FIG. 8).
Note that 30 denotes a latch switch for detecting either one of door conditions of door open, door half-closed, or door full-closed conditions.
In the aforementioned operation of the conventional door closing apparatus, in the event of insufficient operating power or the like, the door closing operation may terminate while the door remains to be in the half-closed condition with the protrusion 9 of the pawl 8 still being engaged with the second projection 7. Consequently, a door closer mechanism is used to bring the door in the half-closed condition automatically into the full closed condition. Examples of this type of door closer are disclosed in Japanese Patent Laid-Open Publication Nos. 96079/1990 and 50045/1994.
It is known that the door closing mechanism employs a construction wherein a latch lever rotating the rotatable shaft of the latch is abutted on an active latch secured to an active lever which ascends and descends by the electric motor so that the latch lever is rotated according to the operation of the active latch. Upon detection of the half-closed condition of the door, the electric motor operates the active lever, such operation being transmitted via the active latch to the latch lever and automatically moving the latch from a position (half-latch status) corresponding to the half-closed condition of the door to a position (full-latch status) corresponding to the full-closed condition of the door according to the rotation of the latch lever.
However, the conventional door closing apparatus operate on a procedure, wherein the electric motor activates closing operation upon sensing that the latch switch is turned on or off, thereby creating a slight timing lag between the moment the latch switch is turned on or off and the moment the door reaches the half-closed condition, wherefore it cannot necessarily be maintained that the electric motor is operated for closing the door upon detecting the half-closed condition of the door. Further, there is another adverse factor, namely, a possibility that the closing operation is continued because of the lack of detection of the completely closed condition of the door.